Rotary rock bit



Feb. 25, 1930. .1. GRANT ET AL 1,748,341

ROTARY ROCK BIT Filed July 3, 1926 A TT ORNEYS.

Patented Feb. 25, 1930 UNITED STATES lPATENT OFFICE JOHN GRANT, 0F LOS ANGELES, AND STEWART L. CAMPBELL, 0F BERKELEY, CALI- FORNIA, SAID CAMPBELL ASSIGNOR TO SAID GRANT ROTARY ROCK BIT Application led July 3, 1926. Serial No. 120,326.`

` l0 or percussion drilling is best suited to certain other types. In present day practice it is necessary to remove entirely one set of tools from the hole in order to insert another set of tools and in order to change the style of drill- 5 ing. This has always been inconvenient, time-consuming and costly, and in some cases ma be practically impossible.

ur invention provides a combination tool with which either variety of drilling oper- 0 ations may be carried on without removal of the tool from the hole. In designing an illustrative embodiment of the invention we have produced the form of combination drill here shown, and one that obtains its driving power from a rotary drill stem; but the invention need not, in its broadest aspects, be necessarily limited to such type of initial drive. However, using an initial rotary drive, the invention proceeds further to the 0 accomplishment of additional objects in that it` provides means for the operation of the percussion elements by virtue of the initial rotation; and further that its percussion elements are automatically thrown into operation by virtue of the rotary drag on the bit. Thus, in the form shown herein, the tool as a whole is rotated in the usual manner from the top of the hole. If the rotary cutters are cutting in a relatively soft formation, to which that style of .cutting is peculiarly adapted, the rotary drag on the cutters is not so great as when harder or rock formation is being cut. In the first named i11- stance the tool is so constructed that the lesser rotary drag will cause relatively little or no percussion action of the percussion drilling elements; whereas if the rotary drag' increases, due to drilling in harder formations, the action of the percussion elements is relatively increased until, 11i a limiting case,

there may be practically no rotary cutting action but the percussion elements may be acting at full capacity to do substantially all, if not all, of the drilling.

The foregoing objects, together with others, and corresponding accomplishments of the invention, will be best understood from the following detailed description of a typical illustrative embodiment of the invention, reference for this purpose being had to the accompanying drawings, in which:

Fig. 1 is an elevation of the complete bit, a portion of the shell being broken away to better shown the construction; Fig. 2 is an axial section through the shell showing portions of the structure in elevation and portions in section; Fig. 3 is a section as seen on the line 3 3 of Fig. 2; and Fi 4 is a section as seen upon the line 44 of ig. 2.

Referring with more particularity to the drawing, 5 indicates a shell, within which is mounted a body 6 secured to the shell so that it will be constrained to rotate therewith. At the bottom of the body are cutting teeth 1la providing a milling cutter.

Mounted within the body and shell is a rotatable arbor 7 which also serves as a shank for the tool. Arranged within the body so as to be longitudinally reciprocable are cutters 8 which operate by percussion upon the formation and are actuated by rotation of the arbor within the body.

The particular shell shown is of tubular form with a bore reduced in diameter at the upper end to provide a shoulderQ. At its lower end it has longitudinal slits l0 t0 accommodate the percussion cutters.

The body 6 is cylindrical having a cutter portion 1l at the lower end of enlarged diameter to correspond with the outer diameter of the shell. The external diameter of the upper portion of the body is such that it Will provide a sliding lit with the shell. The length is such that it willlend short of the shoulder 9 on the shell, when the enlarged,

portion of the body is abuttedagainstthe lower end of the shell. There'are slotslOa in the body adapted to registerwith the slots l0 in the shell. These slits are greater in longitudinal extent than the slits 10, extendto provide guides for the cutters. In order to hold in registration the body 6 and the shell so that the slits are registered, dowel ins on the body are arranged to regisa ter with corresponding recesses on the shell.

e gressively move upwardly to their upper lim- The arbor 7 has a shank 16 provided with the usual tapered and threaded pin at the upper end for attachment to a rotary drill pipe. The shank'is threaded to receive a locking sleeve 17 for holding the arbor in position on the shell and the parts in proper assembled relation. The arbor is enlarged in diameter at 18 and still further enlarged at 19 to fit within the corresponding bore of the shell above the body and provide a thrust portion. At the lower end of the arbor -is a stem 20 of reduced diameter ending short of the lower end of the body and vjournalled at its lower end in the reduced part 12a of bore 12. On the stem is an annular cam 21 having a high portion 22 and a lower portion 23. The construction is such that the lock sleeve 17 holds the arbor and shell in assembled relation. The shell may be vsecured to the body by suitable set screws 24. Upon removing thel lock sleeve 17 and screws 24, the arbor and body may be removed through the lower end of the shell, and then the arbor slipped from the body.

Disposed so that they may slide longitudinall within the shell and within the slots in the liiody are the percussion cutters 8. These cutters are provided with hammer ends 25 arrangedto project through the slits 10. The cutter Shanks 26 are arranged to slidably engage with the internal wall of the shell. At their upper ends they are stepped inwardly as in.- dicated by-27 to provi e seats'for compression springs 28. The compression springs tend to force the percussion cutters downwardly and such downward movement is limited by the cam 21. There are four percussion cutters shown and all are of the .same

construction. O n the inner wall of their Shanks they` are provided with lrecesses 30` within which the cam 21 may play. The upper shoulder of each recess rests upon the upper facevof the cam. The cam surface is, in this particular design, shown as being a continuous spiral` of onerevolution, so that the cutters project different longitudinal distances.

`Upon rotating the arbor within the body, the percussion cutters will be caused to proit',-th'e upper shoulder riding to the high spot of. the cam and then droppingA to the low spot and thereby delivering a blow.

. The compression springs 28 cause the outward movement. Thus, by rotating the ar-l bor, the percussion cutters are successively projected outwardly to produce blows. The tool is operated by rotating the latter. The action of the cam and springs is such as to .exert a-yielding rotary force upon the body and shell. Tf the reacting force is not too great, the cutters will be rotated and the milling teeth will cause rotary abrasion of the formation. However, if sutlicient drag is exerted the arbor will slip within the shell and body causing arelative rotation between the-arbor and body. This causes the percussion cutters to be operated thereby assisting in the operation.

The foregoing description has set out the operation of the device on the assumption that the cutters 25 perform only percussion drilling, while the rotary drilling is done exclusively by the rotary cutting teeth 11a. The device, however, is capable of another mode of operation in which the cutters 25 perform both the rotary and percussion drilling.

It will be noted that the arrangement is such that at least one cutter 25 projects below the lower end of the body-below the rotary cutters 11aand will therefore be in contact `with the bottom of the hole. By forming' the cutters 25 with suitable lcutting edges, as by making them sharp as shown'in the drawings, these cutters 25 may also perform rotary drilling, when the circumstances are such that these cutters are being rotated rather than reciprocated. It will vbe understood from what has been .described hereinbefore that, under certain conditions, the cutters 25 are rotated with the body; and underl those conditions they may perform rotary drilling. Under other conditions the cutters 25 are reciprocated, rather thanV rotated, and under those conditions the cutters 25 will then perform percussion drilling. The invention, as claimed in the following claims therefore contemplates not only a combination where one ino set of rotary cutters perform rotary drilling and another set perform percussion drilling virtue of rotary l ing said percussion cutters operated by slippage between said body-and said shank. 2. 'A tool of the character described comprising a body havlng cutters adapted to cut formation by rotation relative thereto, a shank provided with an arbor yieldably held against rotation therein, reciproca-ble percussion cutters mounted in said body to be rotated therewith, and actuating means for reciprocating said percussion cutters operated by rotation 0f said arbor within said body.

3. A tool of the character described comprising a body having cutters adapted to cut formation 'by rotation relative thereto, an arbor mounted for rotation within said body, reciprocable percussion cutters mounted in said body so as to be rotated therewith, means on said arbor cooperating with said -cutters to reciprocate the latter upon rotation therewith, an annular cam on said varbor engaging said cutters to reciprocate the latter upon rotation of said arbor within said body.

5. A tool of the character described comprising a body having cutters adapted to cut formation by rotation relative thereto, an arbor mounted for rotation with said body, reciprocable percussion cutters mounted in said body so as to be rotated therewith, resilient means tending to project said cutters, a cam on said arbor cooperating with said cutters to retract the latter upon rotation of said arbor within said body.

6. A tool of the class described comprising a body having cutters at the end adapted to cut formation by rotation relative thereto, longitudinally extending slots, an arbor mounted for rotatibn within said body, reciprocable percussion cutters mounted in the slots of said body so as to be rotated therewith, cam means on said arbor cooperating with said cutters to reciprocate the latter upon rotation of said arbor within said body.

7 A tool of thecharacter described comprising a body having longitudinally extending slots and a cutter adapted to cut formation by rotation relative thereto, an arbor mounted for rotation. with said body, reciprocable percussion cutters mounted in the slots of said body so as to be rotated therewith, resilient means tending to project said cutters, cam means on said arbor cooperating with said cutters to retract the latter against the action of said resilient means and to permit projection of the latter by said resilient means.

8. A tool of the character described comprising a body having longitudinally extending slots and a cutter adapted to cut formation by rotation relative thereto, an arbor mounted for rotation wit-hin said body, re-

` cinrocable percussion cutters mounted in the slots of said body so as to be rotated therewith, each of said cutters having a follower portion, a cam on said arbor cooperating with the follower portion of said cutters to retract the latter upon rotation of said arbor within said body, and resilient means tending to project said cutters.

9. A tool of the character described comprising a body having longitudinally extending slots and a cutter adapted to cut formation by rotation relative thereto, an arbor mounted for rotation within said body, reciprocable percussion cutters mounted in the slots of said body so as to be rotated therewith and having follower recesses, an annular cam on said arbor operating within said recesses solas to retract said cutters and then release the same for projection, and resilient means tending to project said cutters.

l0. A tool of the character described comprising a body having a longitudinally eX- tending slot and a cutter adapted to cut formation by rotation relative thereto, a shell detachably mounted over said body, an arbor mounted for rotation within said body and having a thrust portion of enlarged diameter, a lock sleeve mounted on said arbor and engaging one end of said shell, a reciprocable percussion cutter mounted in the slot of said body so as to be rotated therewith and having follower recesses, and an annular cam bn said arbor operating within said recesses so as to retract said cutter and then release the same for projection, and a spring disposed in said slot tending to proj ect said cutter.

ll. A tool of the character described, embodying a body and a shank rotatable relative to each other, cutters mounted in the body for rotation therewith and for vertical reciprocation relative thereto, said cutters having formation engaging faces adapted to cut formation by reciprocation relative thereto, other cutters on the body adapted to cut formation by rotation relative thereto, and means for causing reciprocation of said first mentioned cutters by virtue of relative rotation between the shank and body.

12. A tool of the character described, embodying a body and a shank rotatable relative to each other, cutters mounted in the body for rotation therewith and for vertical reciprocation relative thereto, said cutters having formation engaging faces adapted to cut formation by reciprocation relative thereto, other cutters on the body adapted to cut formation by rotation relative thereto, and means for causing reciprocation of said first mentioned cutters by virtue of relative rotation between the shank and body; said means comprising a vertically acting cam adapted to alternately lift and drop the cutters upon relative rotation between the shank-and body.

13. A tool of the character described, em-

bodying a body and a shank rotatable relative to each other, cutters mounted in the body for rotation therewith and for vertical reciprocation relative thereto, said cutters having formation engaging faces adapted to cut formation by reciprocation relative thereto, other cutters on the body adapted to cut formation by rotation relative thereto, and means for causing reciprocation of said first mentioned cutters by virtue of relative rotation between the shank'and body; said means comprising a vertically acting cam adapted to alternately lift and drop the cutters upon relative rotation between the shank and body, and springs urging the cutters downwardly against the action of said cam.

14. A tool of the character described, comprising a mandrel, a cutter rotatable with and longitudinally reciprocable with rela.- tion to the mandrel, said cutter having a formation engaging face adapted to cut the formation either by rotation or reciprocation relative thereto, mean-s operable by Virtue of rotary drag on the cutterto cause relative vertical reciprocation thereof; and an independent cutter rotatable by the mandrel and adapted to cut formation by rotation relative thereto.

15. A tool of the character described, comprising a body and a mandrel rotatable relative to each other, cutters mounted in the body for rotation therewith and for vertical reciprocation relative thereto, said cutters having formation engagingfaces adapted to cut formation either by rotation relative thereto or by reciprocation relative thereto, means for causing reciprocation of said cutters by virtue of relative rotation between the mandrel and body; and an independent cutter on the body and adapted to cut formation by rotation relative thereto.

. Y 16. A tool of the character described, comprising a mandrel, a body mounted thereon for yieldably rotating therewith, vreciprocable critters mounted in the body and having formation engaging faces adapted to cut-the formation either by rotation or by percussion, actuating means for reciprocating said cutters operated by slippage between said ter on the body and adaptedi to cut formation by rotation relative thereto.

In witness that I claim the foregoing I have hereunto subscribed my name this 18thday of June, 1926.v

JOHN GRANT. In witness that I claim the foregoing I have hereunto subscribed vmy name this 26 day of June, 1926. STEWART L. CAMPBELL. 

